Surface waves in an incompressible fluid - Resonant instability due to velocity shear

Journal Article · Mon Jan 01 04:00:00 EST 1990 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/168317· OSTI ID:6997388

Hollweg, J V; Yang, G; Cadez, V M; Gakovic, B ^[1]

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1. New Hampshire Univ., Durham (USA) Institut za Fiziku, Belgrade (Yugoslavia) Sarajevo Univerzitet (Yugoslavia)

The effects of velocity shear on the resonance absorption of incompressible MHD surface waves are studied. It is found that there are generally values of the velocity shear for which the surface wave decay rate becomes zero. In some cases, the resonance absorption goes to zero even for very small velocity shears. It is also found that the resonance absorption can be strongly enhanced at other values of the velocity shear, so the presence of flows may be generally important for determining the effects of resonance absorption, such as might occur in the interaction of p-modes with sunspots. Resonances leading to instability of the global surface mode can exist, and instability can occur for velocity shears significantly below the Kelvin-Helmholtz threshold. These instabilities may play a role in the development or turbulence in regions of strong velocity shear in the solar wind or the earth's magnetosphere. 27 refs.

• OSTI ID: 6997388
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 349; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
640201 -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
FLUID FLOW
FLUID MECHANICS
HELMHOLTZ INSTABILITY
HYDROMAGNETIC WAVES
INCOMPRESSIBLE FLOW
INSTABILITY
MECHANICS
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
RESONANCE
SHEAR
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR WIND
STARSPOTS
STELLAR ACTIVITY
SUNSPOTS
TURBULENCE